Which is not an electron carrier

Options

A. CoQ
B. Cyt c
C. Cyt a
D. `H_(2)O`

Answer

To determine which of the given options is not an electron carrier, we can analyze each option based on their roles in biological processes, particularly in cellular respiration and photosynthesis.

### Step-by-Step Solution:

1. **Understanding Electron Carriers**:
- Electron carriers are molecules that accept and transport electrons during biochemical reactions. They play a crucial role in the electron transport chain, which is essential for energy production in cells.

2. **Analyzing the Options**:
- **Coenzyme Q (Ubiquinone)**: This is an electron carrier that transports electrons within the mitochondrial membrane. It is soluble in fats and plays a key role in the electron transport chain.
- **Cytochrome C**: This is another well-known electron carrier that transfers electrons between complexes in the electron transport chain, particularly in mitochondria.
- **Cytochrome A**: Similar to cytochrome C, cytochrome A is also an electron carrier involved in the electron transport chain.
- **Water**: Water does not act as an electron carrier. Instead, it undergoes photolysis during photosynthesis, where it is split to release electrons, but it does not transport electrons itself.

3. **Identifying the Correct Answer**:
- Among the options provided, coenzyme Q, cytochrome C, and cytochrome A are all electron carriers. However, water does not function as an electron carrier. Therefore, the correct answer to the question "Which is not an electron carrier?" is **water**.

### Final Answer:
**Water is not an electron carrier.**

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